Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/riscv/riscv/elf_machdep.c
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1 /*- 2 * Copyright 1996-1998 John D. Polstra. 3 * Copyright (c) 2015 Ruslan Bukin <br@bsdpad.com> 4 * Copyright (c) 2016 Yukishige Shibata <y-shibat@mtd.biglobe.ne.jp> 5 * All rights reserved. 6 * 7 * Portions of this software were developed by SRI International and the 8 * University of Cambridge Computer Laboratory under DARPA/AFRL contract 9 * FA8750-10-C-0237 ("CTSRD"), as part of the DARPA CRASH research programme. 10 * 11 * Portions of this software were developed by the University of Cambridge 12 * Computer Laboratory as part of the CTSRD Project, with support from the 13 * UK Higher Education Innovation Fund (HEIF). 14 * 15 * Redistribution and use in source and binary forms, with or without 16 * modification, are permitted provided that the following conditions 17 * are met: 18 * 1. Redistributions of source code must retain the above copyright 19 * notice, this list of conditions and the following disclaimer. 20 * 2. Redistributions in binary form must reproduce the above copyright 21 * notice, this list of conditions and the following disclaimer in the 22 * documentation and/or other materials provided with the distribution. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37 #include <sys/cdefs.h> 38 __FBSDID("$FreeBSD: releng/11.2/sys/riscv/riscv/elf_machdep.c 301205 2016-06-02 15:14:40Z br $"); 39 40 #include <sys/param.h> 41 #include <sys/kernel.h> 42 #include <sys/systm.h> 43 #include <sys/exec.h> 44 #include <sys/imgact.h> 45 #include <sys/linker.h> 46 #include <sys/proc.h> 47 #include <sys/sysctl.h> 48 #include <sys/sysent.h> 49 #include <sys/imgact_elf.h> 50 #include <sys/syscall.h> 51 #include <sys/signalvar.h> 52 #include <sys/vnode.h> 53 54 #include <vm/vm.h> 55 #include <vm/pmap.h> 56 #include <vm/vm_param.h> 57 58 #include <machine/elf.h> 59 #include <machine/md_var.h> 60 61 struct sysentvec elf64_freebsd_sysvec = { 62 .sv_size = SYS_MAXSYSCALL, 63 .sv_table = sysent, 64 .sv_mask = 0, 65 .sv_errsize = 0, 66 .sv_errtbl = NULL, 67 .sv_transtrap = NULL, 68 .sv_fixup = __elfN(freebsd_fixup), 69 .sv_sendsig = sendsig, 70 .sv_sigcode = sigcode, 71 .sv_szsigcode = &szsigcode, 72 .sv_name = "FreeBSD ELF64", 73 .sv_coredump = __elfN(coredump), 74 .sv_imgact_try = NULL, 75 .sv_minsigstksz = MINSIGSTKSZ, 76 .sv_pagesize = PAGE_SIZE, 77 .sv_minuser = VM_MIN_ADDRESS, 78 .sv_maxuser = VM_MAXUSER_ADDRESS, 79 .sv_usrstack = USRSTACK, 80 .sv_psstrings = PS_STRINGS, 81 .sv_stackprot = VM_PROT_ALL, 82 .sv_copyout_strings = exec_copyout_strings, 83 .sv_setregs = exec_setregs, 84 .sv_fixlimit = NULL, 85 .sv_maxssiz = NULL, 86 .sv_flags = SV_ABI_FREEBSD | SV_LP64, 87 .sv_set_syscall_retval = cpu_set_syscall_retval, 88 .sv_fetch_syscall_args = cpu_fetch_syscall_args, 89 .sv_syscallnames = syscallnames, 90 .sv_schedtail = NULL, 91 .sv_thread_detach = NULL, 92 .sv_trap = NULL, 93 }; 94 INIT_SYSENTVEC(elf64_sysvec, &elf64_freebsd_sysvec); 95 96 static Elf64_Brandinfo freebsd_brand_info = { 97 .brand = ELFOSABI_FREEBSD, 98 .machine = EM_RISCV, 99 .compat_3_brand = "FreeBSD", 100 .emul_path = NULL, 101 .interp_path = "/libexec/ld-elf.so.1", 102 .sysvec = &elf64_freebsd_sysvec, 103 .interp_newpath = NULL, 104 .brand_note = &elf64_freebsd_brandnote, 105 .flags = BI_CAN_EXEC_DYN | BI_BRAND_NOTE 106 }; 107 108 SYSINIT(elf64, SI_SUB_EXEC, SI_ORDER_FIRST, 109 (sysinit_cfunc_t) elf64_insert_brand_entry, 110 &freebsd_brand_info); 111 112 static Elf64_Brandinfo freebsd_brand_oinfo = { 113 .brand = ELFOSABI_FREEBSD, 114 .machine = EM_RISCV, 115 .compat_3_brand = "FreeBSD", 116 .emul_path = NULL, 117 .interp_path = "/usr/libexec/ld-elf.so.1", 118 .sysvec = &elf64_freebsd_sysvec, 119 .interp_newpath = NULL, 120 .brand_note = &elf64_freebsd_brandnote, 121 .flags = BI_CAN_EXEC_DYN | BI_BRAND_NOTE 122 }; 123 124 SYSINIT(oelf64, SI_SUB_EXEC, SI_ORDER_ANY, 125 (sysinit_cfunc_t) elf64_insert_brand_entry, 126 &freebsd_brand_oinfo); 127 128 static int debug_kld; 129 SYSCTL_INT(_kern, OID_AUTO, debug_kld, 130 CTLFLAG_RW, &debug_kld, 0, 131 "Activate debug prints in elf_reloc_internal()"); 132 133 struct type2str_ent { 134 int type; 135 const char *str; 136 }; 137 138 void 139 elf64_dump_thread(struct thread *td, void *dst, size_t *off) 140 { 141 142 } 143 144 /* 145 * Following 4 functions are used to manupilate bits on 32bit interger value. 146 * FIXME: I implemetend for ease-to-understand rather than for well-optimized. 147 */ 148 static uint32_t 149 gen_bitmask(int msb, int lsb) 150 { 151 uint32_t mask; 152 153 if (msb == sizeof(mask) * 8 - 1) 154 mask = ~0; 155 else 156 mask = (1U << (msb + 1)) - 1; 157 158 if (lsb > 0) 159 mask &= ~((1U << lsb) - 1); 160 161 return (mask); 162 } 163 164 static uint32_t 165 extract_bits(uint32_t x, int msb, int lsb) 166 { 167 uint32_t mask; 168 169 mask = gen_bitmask(msb, lsb); 170 171 x &= mask; 172 x >>= lsb; 173 174 return (x); 175 } 176 177 static uint32_t 178 insert_bits(uint32_t d, uint32_t s, int msb, int lsb) 179 { 180 uint32_t mask; 181 182 mask = gen_bitmask(msb, lsb); 183 184 d &= ~mask; 185 186 s <<= lsb; 187 s &= mask; 188 189 return (d | s); 190 } 191 192 static uint32_t 193 insert_imm(uint32_t insn, uint32_t imm, int imm_msb, int imm_lsb, 194 int insn_lsb) 195 { 196 int insn_msb; 197 uint32_t v; 198 199 v = extract_bits(imm, imm_msb, imm_lsb); 200 insn_msb = (imm_msb - imm_lsb) + insn_lsb; 201 202 return (insert_bits(insn, v, insn_msb, insn_lsb)); 203 } 204 205 /* 206 * The RISC-V ISA is designed so that all of immediate values are 207 * sign-extended. 208 * An immediate value is sometimes generated at runtime by adding 209 * 12bit sign integer and 20bit signed integer. This requests 20bit 210 * immediate value to be ajusted if the MSB of the 12bit immediate 211 * value is asserted (sign-extended value is treated as negative value). 212 * 213 * For example, 0x123800 can be calculated by adding upper 20 bit of 214 * 0x124000 and sign-extended 12bit immediate whose bit pattern is 215 * 0x800 as follows: 216 * 0x123800 217 * = 0x123000 + 0x800 218 * = (0x123000 + 0x1000) + (-0x1000 + 0x800) 219 * = (0x123000 + 0x1000) + (0xff...ff800) 220 * = 0x124000 + sign-extention(0x800) 221 */ 222 static uint32_t 223 calc_hi20_imm(uint32_t value) 224 { 225 /* 226 * There is the arithmetical hack that can remove conditional 227 * statement. But I implement it in straightforward way. 228 */ 229 if ((value & 0x800) != 0) 230 value += 0x1000; 231 return (value & ~0xfff); 232 } 233 234 static const struct type2str_ent t2s[] = { 235 { R_RISCV_NONE, "R_RISCV_NONE" }, 236 { R_RISCV_64, "R_RISCV_64" }, 237 { R_RISCV_JUMP_SLOT, "R_RISCV_JUMP_SLOT" }, 238 { R_RISCV_RELATIVE, "R_RISCV_RELATIVE" }, 239 { R_RISCV_JAL, "R_RISCV_JAL" }, 240 { R_RISCV_CALL, "R_RISCV_CALL" }, 241 { R_RISCV_PCREL_HI20, "R_RISCV_PCREL_HI20" }, 242 { R_RISCV_PCREL_LO12_I, "R_RISCV_PCREL_LO12_I" }, 243 { R_RISCV_PCREL_LO12_S, "R_RISCV_PCREL_LO12_S" }, 244 { R_RISCV_HI20, "R_RISCV_HI20" }, 245 { R_RISCV_LO12_I, "R_RISCV_LO12_I" }, 246 { R_RISCV_LO12_S, "R_RISCV_LO12_S" }, 247 }; 248 249 static const char * 250 reloctype_to_str(int type) 251 { 252 int i; 253 254 for (i = 0; i < sizeof(t2s) / sizeof(t2s[0]); ++i) { 255 if (type == t2s[i].type) 256 return t2s[i].str; 257 } 258 259 return "*unknown*"; 260 } 261 262 /* 263 * Currently kernel loadable module for RISCV is compiled with -fPIC option. 264 * (see also additional CFLAGS definition for RISCV in sys/conf/kmod.mk) 265 * Only R_RISCV_64, R_RISCV_JUMP_SLOT and RISCV_RELATIVE are emitted in 266 * the module. Other relocations will be processed when kernel loadable 267 * modules are built in non-PIC. 268 * 269 * FIXME: only RISCV64 is supported. 270 */ 271 static int 272 elf_reloc_internal(linker_file_t lf, Elf_Addr relocbase, const void *data, 273 int type, int local, elf_lookup_fn lookup) 274 { 275 Elf_Size rtype, symidx; 276 const Elf_Rela *rela; 277 Elf_Addr val, addr; 278 Elf64_Addr *where; 279 Elf_Addr addend; 280 uint32_t before32_1; 281 uint32_t before32; 282 uint64_t before64; 283 uint32_t* insn32p; 284 uint32_t imm20; 285 int error; 286 287 switch (type) { 288 case ELF_RELOC_RELA: 289 rela = (const Elf_Rela *)data; 290 where = (Elf_Addr *)(relocbase + rela->r_offset); 291 insn32p = (uint32_t*)where; 292 addend = rela->r_addend; 293 rtype = ELF_R_TYPE(rela->r_info); 294 symidx = ELF_R_SYM(rela->r_info); 295 break; 296 default: 297 printf("%s:%d unknown reloc type %d\n", 298 __FUNCTION__, __LINE__, type); 299 return -1; 300 } 301 302 switch (rtype) { 303 case R_RISCV_NONE: 304 break; 305 306 case R_RISCV_64: 307 case R_RISCV_JUMP_SLOT: 308 error = lookup(lf, symidx, 1, &addr); 309 if (error != 0) 310 return -1; 311 312 val = addr; 313 before64 = *where; 314 if (*where != val) 315 *where = val; 316 317 if (debug_kld) 318 printf("%p %c %-24s %016lx -> %016lx\n", 319 where, 320 (local? 'l': 'g'), 321 reloctype_to_str(rtype), 322 before64, *where); 323 break; 324 325 case R_RISCV_RELATIVE: 326 val = relocbase + addend; 327 328 before64 = *where; 329 if (*where != val) 330 *where = val; 331 332 if (debug_kld) 333 printf("%p %c %-24s %016lx -> %016lx\n", 334 where, 335 (local? 'l': 'g'), 336 reloctype_to_str(rtype), 337 before64, *where); 338 break; 339 340 case R_RISCV_JAL: 341 error = lookup(lf, symidx, 1, &addr); 342 if (error != 0) 343 return -1; 344 345 val = addr - (Elf_Addr)where; 346 if ((val <= -(1UL << 20) || (1UL << 20) <= val)) { 347 printf("kldload: huge offset against R_RISCV_JAL\n"); 348 return -1; 349 } 350 351 before32 = *insn32p; 352 *insn32p = insert_imm(*insn32p, val, 20, 20, 31); 353 *insn32p = insert_imm(*insn32p, val, 10, 1, 21); 354 *insn32p = insert_imm(*insn32p, val, 11, 11, 20); 355 *insn32p = insert_imm(*insn32p, val, 19, 12, 12); 356 357 if (debug_kld) 358 printf("%p %c %-24s %08x -> %08x\n", 359 where, 360 (local? 'l': 'g'), 361 reloctype_to_str(rtype), 362 before32, *insn32p); 363 break; 364 365 case R_RISCV_CALL: 366 /* 367 * R_RISCV_CALL relocates 8-byte region that consists 368 * of the sequence of AUIPC and JALR. 369 */ 370 /* calculate and check the pc relative offset. */ 371 error = lookup(lf, symidx, 1, &addr); 372 if (error != 0) 373 return -1; 374 val = addr - (Elf_Addr)where; 375 if ((val <= -(1UL << 32) || (1UL << 32) <= val)) { 376 printf("kldload: huge offset against R_RISCV_CALL\n"); 377 return -1; 378 } 379 380 /* Relocate AUIPC. */ 381 before32 = insn32p[0]; 382 imm20 = calc_hi20_imm(val); 383 insn32p[0] = insert_imm(insn32p[0], imm20, 31, 12, 12); 384 385 /* Relocate JALR. */ 386 before32_1 = insn32p[1]; 387 insn32p[1] = insert_imm(insn32p[1], val, 11, 0, 20); 388 389 if (debug_kld) 390 printf("%p %c %-24s %08x %08x -> %08x %08x\n", 391 where, 392 (local? 'l': 'g'), 393 reloctype_to_str(rtype), 394 before32, insn32p[0], 395 before32_1, insn32p[1]); 396 break; 397 398 case R_RISCV_PCREL_HI20: 399 val = addr - (Elf_Addr)where; 400 insn32p = (uint32_t*)where; 401 before32 = *insn32p; 402 imm20 = calc_hi20_imm(val); 403 *insn32p = insert_imm(*insn32p, imm20, 31, 12, 12); 404 405 if (debug_kld) 406 printf("%p %c %-24s %08x -> %08x\n", 407 where, 408 (local? 'l': 'g'), 409 reloctype_to_str(rtype), 410 before32, *insn32p); 411 break; 412 413 case R_RISCV_PCREL_LO12_I: 414 val = addr - (Elf_Addr)where; 415 insn32p = (uint32_t*)where; 416 before32 = *insn32p; 417 *insn32p = insert_imm(*insn32p, addr, 11, 0, 20); 418 419 if (debug_kld) 420 printf("%p %c %-24s %08x -> %08x\n", 421 where, 422 (local? 'l': 'g'), 423 reloctype_to_str(rtype), 424 before32, *insn32p); 425 break; 426 427 case R_RISCV_PCREL_LO12_S: 428 val = addr - (Elf_Addr)where; 429 insn32p = (uint32_t*)where; 430 before32 = *insn32p; 431 *insn32p = insert_imm(*insn32p, addr, 11, 5, 25); 432 *insn32p = insert_imm(*insn32p, addr, 4, 0, 7); 433 if (debug_kld) 434 printf("%p %c %-24s %08x -> %08x\n", 435 where, 436 (local? 'l': 'g'), 437 reloctype_to_str(rtype), 438 before32, *insn32p); 439 break; 440 441 case R_RISCV_HI20: 442 error = lookup(lf, symidx, 1, &addr); 443 if (error != 0) 444 return -1; 445 446 insn32p = (uint32_t*)where; 447 before32 = *insn32p; 448 imm20 = calc_hi20_imm(val); 449 *insn32p = insert_imm(*insn32p, imm20, 31, 12, 12); 450 451 if (debug_kld) 452 printf("%p %c %-24s %08x -> %08x\n", 453 where, 454 (local? 'l': 'g'), 455 reloctype_to_str(rtype), 456 before32, *insn32p); 457 break; 458 459 case R_RISCV_LO12_I: 460 error = lookup(lf, symidx, 1, &addr); 461 if (error != 0) 462 return -1; 463 464 val = addr; 465 insn32p = (uint32_t*)where; 466 before32 = *insn32p; 467 *insn32p = insert_imm(*insn32p, addr, 11, 0, 20); 468 469 if (debug_kld) 470 printf("%p %c %-24s %08x -> %08x\n", 471 where, 472 (local? 'l': 'g'), 473 reloctype_to_str(rtype), 474 before32, *insn32p); 475 break; 476 477 case R_RISCV_LO12_S: 478 error = lookup(lf, symidx, 1, &addr); 479 if (error != 0) 480 return -1; 481 482 val = addr; 483 insn32p = (uint32_t*)where; 484 before32 = *insn32p; 485 *insn32p = insert_imm(*insn32p, addr, 11, 5, 25); 486 *insn32p = insert_imm(*insn32p, addr, 4, 0, 7); 487 488 if (debug_kld) 489 printf("%p %c %-24s %08x -> %08x\n", 490 where, 491 (local? 'l': 'g'), 492 reloctype_to_str(rtype), 493 before32, *insn32p); 494 break; 495 496 default: 497 printf("kldload: unexpected relocation type %ld\n", rtype); 498 return (-1); 499 } 500 501 return (0); 502 } 503 504 int 505 elf_reloc(linker_file_t lf, Elf_Addr relocbase, const void *data, int type, 506 elf_lookup_fn lookup) 507 { 508 509 return (elf_reloc_internal(lf, relocbase, data, type, 0, lookup)); 510 } 511 512 int 513 elf_reloc_local(linker_file_t lf, Elf_Addr relocbase, const void *data, 514 int type, elf_lookup_fn lookup) 515 { 516 517 return (elf_reloc_internal(lf, relocbase, data, type, 1, lookup)); 518 } 519 520 int 521 elf_cpu_load_file(linker_file_t lf __unused) 522 { 523 524 return (0); 525 } 526 527 int 528 elf_cpu_unload_file(linker_file_t lf __unused) 529 { 530 531 return (0); 532 }
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